| 摘要 |
Terephthalic acid is purified by dissolving it at 80-190 DEG C in an aqueous solution containing an alkali-metal or ammonium salt of an organic acid having a dissociation constant between 1.7 x 10-5 and 2 x 10-2 and 5-120 mol. per cent of the corresponding free acid, and then cooling the solution. Specified acids are formic, acetic, propionic, oxalic, tartaric, citric, glycollic and maleic acids. Simultaneously, the solution may be oxidized, reduced or given an adsorption treatment, oxidation with potassium perman ganate or bichromate, or reduction by catalytic hydrogenation, or adsorption with active carbon being described. Examples are given. |
